Adsorption of nucleic acid constituent uracil on copper(II)-loaded, solid peat and soil-derived humic acids
Bibliographic record
Abstract
Humic acids (HA) in compost, peats and soils sorb organic compounds selectively. This paper investigates the micro- and macroscopic properties of solid HAs isolated from a German peat (GHA) and a New Hampshire soil (NHA) using tightly bound copper(II) and nucleic acid constituent uracil adsorption as analytical probes. Isotherm measurements at 5.0–35.0°C show that tightly bound Cu(II) decreases the amount of uracil adsorbed by GHA at mM or lower uracil concentrations whereas previous work revealed the opposite effect for bound Hg(II). Site capacity comparisons are consistent with lower coordination numbers for HA-bound Hg(II) than for HA-bound Cu(II). Low coordination numbers leave Hg(II) sites open for uracil binding. Enthalpy and entropy changes for uracil adsorption on GHA, NHA, their Cu(II) and Hg(II)-loaded forms and on compost-derived HA are linearly correlated, indicating that HAs are free energy buffers. Water and bound metals evidently play major roles in HA-solute interactions and in HA aggregation/disaggregation. Key words: Humic acids, metal binding, nucleic acid constituents, uracil, adsorption, isotherms, thermodynamics
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".